High · published May 20, 2026
Multiple flaws have been identified in `named` related to the handling of DNS messages whose CLASS is not Internet (`IN`) — for example, `CHAOS` or `HESIOD`, or DNS messages that specify meta-classes (`ANY` or `NONE`) in the question section. Specially crafted requests reaching the affected code paths — recursion, dynamic updates (`UPDATE`), zone change notifications (`NOTIFY`), or processing of `IN`-specific record types in non-`IN` data — can cause assertion failures in `named`.
This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.
| Product | Versions | Fixed in |
|---|---|---|
| isc/bind | ≥ 9.11.0, ≤ 9.16.50 | — |
| isc/bind | ≥ 9.18.0, < 9.18.49 | 9.18.49 |
| isc/bind | ≥ 9.20.0, < 9.20.23 | 9.20.23 |
| isc/bind | ≥ 9.21.0, < 9.21.22 | 9.21.22 |